There is known a head-up display (HUD) device having a display unit to emit display light representing a predetermined image, and projecting the display light from the display unit to a front glass or the like of a vehicle, via a reflection member such as a concave surface mirror to cause a user to visually recognize a display image.
In Patent Literature 1, there is disclosed a HUD device which is provided with: a holder to hold a reflection member; and a supporting part to turnably support a holder member about a turning axis, and which is structured to rotatably retain the reflection member. The HUD device according to Patent Literature 1 has a structure in which: one pair of first and second supported parts are provided so as to sandwich the reflection member along the turning axis therebetween; the supporting part is made of a first supporting part to support the first supported part and a second supporting part to support the second supported part; between the first supporting part and the first supported part, a gap to permit movement of the first supporting part is provided; and a restraining part to restrain movement of the second supported part in a turning axis direction of the second supported part is provided at a side at which the second supporting part and the second supported part are disposed.